New U.S. Census projections released Wednesday estimate that Utah will cram another 1 million people within its borders in the next 25 years, making it the fifth fastest-growing state in the nation. Utah families are expected to give birth to most of the new residents, supported by a constant stream of outsiders moving in.

Federal forecasters project Utah will have a population nearing 3.5 million residents in 2030, though state demographers expect even faster growth. They believe the population will actually surpass 4 million by that time.

Utah's neighboring states are seeing similar, or faster, growth. Nevada is expected to more than double its population by 2030, surpassing Utah within the next couple of years. Arizona anticipates doubling its population as well.

Two of the most populous states, Florida and Texas, also are expecting a crush of new residents, according to the report.

Despite the addition of hundreds of thousands of new school-age children, Utah's population will actually get a bit older.

The median age for a Utahn is now 28: half the population is older than that and half is younger. That median age is expected to creep above 30 by 2030. The nation as a whole continues to age at a faster rate. The median age for the United States is 36 and is expected to reach 39 by 2030.

Thank the baby boomers.

Members of that generation, born between 1946 and 1964 in the nation's modern peak of fertility, will start to retire. And they will spur Utah to have the ninth fastest-growing elderly population in the country, with an additional 270,000 people surpassing their 65th birthday.

The graying of Utah will force a state geared around young families to devote more attention - and tax dollars - to health-care costs, prescription drugs and alternative means of transportation for those who no longer can drive, among a host of other issues.

"The need for caregiving will escalate in this society," said Rob Ence, director of AARP of Utah, who expects to see a new generation that will increasingly nurture children at the same time they care for their elderly parents.

Even with the rise of the elderly population, Utah is expected to remain the youngest state.

Right now only Alaska has a smaller percentage of people 65 and older, 5.7 percent to Utah's 8.5. But even Alaska will jump past Utah in the next 25 years.

"Old people don't like living in cold places," said Pam Perlich, senior research economist for the University of Utah's Bureau of Economic and Business Research. Though she noted many elderly people are moving into the burgeoning southern Utah communities in Washington and Iron counties, which she describes as an offshoot of the population boom in Las Vegas.

The growth in states such as Utah, Nevada, Arizona and Idaho indicates that the economy in the Intermountain West is strong and getting stronger, according to Perlich.

"People move where they can work and they stay where they can work," she said.

Families feel they can financially support children in Utah.

And outsiders are continuing to move into the state, whether to retire in the dry desert air of southern Utah, recreate in the northern mountains or join the work force in the metro area.

Utah is now the 34th largest state, and is expected to climb to 31st in the next quarter century.

mcanham@sltrib.com